The present invention relates to a chair having a seat swingable from a normal sitting position to a backward-leaning rest position and back to the normal sitting position.
Chairs known in the art have multiple adjustment functions, such as an adjustment of the vertical position of the seat and adjustments of the seat and the back portions dependently and independently from each other.
However, known constructions of the chairs do not render possible an adjustment of a curve shape of the seat, for a seated person, from the upright seat supporting (lordose) to the back-leaning seat supporting (kyphose).